Method and apparatus for the manufacture of pressed-sheet-glass products



F. L. 0; wanswomu. v METHOD AND APPARATUS- FOR THE MANUFACTURE OF PRESSED SHEET GLASS PRODUCTS.

APPLICATION FILED NOV. 21, I913- Patented J uly 13, 1920.

3 SHEETS-SHEET 1.

s E s s E N l- W F. L. O. WADSWORTH. METHOD AND APPARATUS FOR THE MANUFACTURE OF PRESSED SHEET GLASS PRODUCTS. APPLICATION FILED Nov, 21, I913.

1,346, 57 1 Patented J 1113 13, 1920.

3 SHEETSSHEET 2.

WITNESSES TNJENTOR F. L. 0. WADSWORTH. METHOD AND APPARATUS FOR THE MANUFACTURE OF PRESSED SHEET GLASS PRODUCTS.

APPLICATION FILED N FRANK L. 0. WADSWOBTH, OF PITTSBURGH, PENNSYLVANIA.

Specification of Letters Patent.

Patented July 13,1920.

Application filed November 21, 1913. Serial No. 802.311.

To all whom it may concern Be it known'that I, FRANK L. O. lVAnswou'ri-r, a citizen of the United States, residing at Pittsburgh. in' the county of Allegheny, State of Pennsylvania, have invented a new and useful Method and Apparatus for the Manufacture of Pressed-Sheet-Glass Products, of which the following is a specification.

My invention relates particularly to the manufacture of large glass plates having pressed surfaces; and the principal object of my invention is to produce such plates of any desired size and thickness and of any desired configuration of surface. -Another object of my invention is toproduce such plates free from any internal strain so as to facilitate annealing, and enable such plates to be subsequently cut into small pieces without danger of fracture. Still another object of my invention is to secure practical uniformity in the temperature conditions of the plate at the time the desired surface configuration is imparted to it by the pressing operation so as to attain clean cut and sharply impressed figures of the most intricate and delicate pattern over the entire surface of the plate. Still another object of my invention is to produce a combination of means and instrumentalities whereby the above objects can be effectively and efiiciently secured at small expense. My invention therefore relates in part to a method of operation and in part to the apparatus by which that method is carried into effect. I will first describe the general process which I employ, and then the particular forms of apparatus which I have devised for the carrying on' of the said process.

The general series of steps involved in the practice of my improved method of manufacture comprise: let, the spreading of the glass while in a molten state to the general size and form required for the completed article; 2nd, the re-heating and softening of one side of the spread blank so as to remove any inequalities of temperature that may have resulted from the spreading operation and bring the whole of the re-heated side to the proper state for a subsequent reformation; 3rd, the figuring or re-formation of the re-heated side by pressing it against a die or matrix cut to the desired pattern of the finished article; and 4th, the transfer of the pressed article to an annealing leer and the gradual reduction therein to a temperature at which the article can be handled all of these steps being carried on successively and consecutively while the article still retains a portion of the initial heat of the molten mass from which it was originally formed. This process is distinguished primarily from those which are now in use by the employment of the second step of the operation, and the particular advantages of the method herein described and claimed are due to the introduction of this second step.

In order to effectively carry out the above process certain new and novel apparatus and combinations of instrumentalities have been devised which are illustrated in the accompanying drawings, forming a part of this specification, in which Figure 1 illustrates in plan view a general diagrammatic arrangement of the parts of one apparatus suitable for the practice of my method; Fig.

2 is a partial vertical section on the line XX of Fig. 1; Fig. 3 is a partial end View and cross-section of a part of the apparatustaken on the line YY of Fig. 2; Fig. 4: is a detail of one of the constructional features; Fig. 5 is a plan view of a second form of apparatus for the practice of my invention; Fig. 6 is a longitudinal section of this apparatus on the line Z-Z of Fig. 5; Fig. 7 is a partial end View of certain features of construction of the apparatus shown in Figs. 5 and 6; Figs. 8 and 9 are diagrammatic views illustrating details of the operation of certain parts of the mechanism; and Figs. 10, 11, 12 and 13 illustrate still another form of apparatus which may be employed in my improved method of operation. It will be understood that these drawings are not complete working drawings of my improved apparatus, but are, in part, diagrammatic in character, and are intended to illustrate, as clearly as possible, only the main features of the forms of mechanism which I may employ in the practice of my process.

Referring first to the form of apparatus shown in Figs. 1 to 4: 1 indicates the table or support on which the glass is first spread to the required sheet form and 2 indicates the roller or equivalent device by which this spreading is effected. In this operation the molten glass is teemed or deposited in a mass in front, 2'. e., to the left, of the roll 2 between the guns 3, 3 and is rolled out into sheet form either by advancing the roll over the table or preferablyas in the apparatus illustratedby moving the table 1 under the roll 2. This latter movement is effected by means of a ram 4, the plunger of which engages with the end of the carriage 5 on which the table 1 is mounted. The movement of the plunger may be effected by either hydraulic or pneumatic pressure or by any other suitable form of motor having proper control mechanism for securing the desired movement of the table support and table. As shown in the drawings the plunger is provided with a rack which engages with a gear (which when the ram is operated by a motor may serve itself as a motor driven pinion for the ram) and this gear is connected by a chain or other form of positively driven transmission to the axis of the roll 2 so that the peripheral speed of the roll is the same as the forward movement of the table.

The roll 2 is preferably mounted on a pivoted swinging frame 7 and can be lifted away from the table or lowered upon it by a lever and eccentrics 8 engaging the ends of rods 9 projecting upward from the arms of the swinging frame 7. The thickness of glass which 'is spread upon the table is governed by the vertical adjustment of the roll with respect thereto, this adjustment being determined by the setting of the lever and eccentric 8, or by collars on the roll 2 or preferably as shown, by the use of the usual trangs on the edges of the table 1.

The carriage 5 which supports the rolling table consists of an open rectangular base frame provided'with track wheels 10 and having two end standards or posts 11, 11 forked at their" upper extremities to receive trunnions on the ends of the table, and provided with laterally extending arms 12 (see Fig. which carry suitable spring catches or pins for retaining the table in a substantially horizontal position either side up. By withdrawing or releasing these catches the table can be rotated on its trunnions within the open base frame as indicated by the dotted circle of Fig. 3.

13 indicates a heating furnace which is preferably located just in advance of the spreading roll 2 and is of such crosssectional form (as shown in Fig. as to receive the table 1 and the carriage 5 as it is moved forward to perform the spreading operation. The side walls of this furnace are provided with slots 14, 14 to receive and protect the edges of the table 1 and with laterally extended flanges 15, 15 which cover and protect the lower rectangular framework and track wheels of the table carriage 5. The length of this furnace is slightly less than the length of the table 1 so as to likewise protect the end parts of the table and table support, when the latter is in position within the furnace. Both the free width and length of the chamber 13 is less than the width and length of the spread sheet of glass so that the latter constitutes in effect the floor of the heating chamber when it is brought within it, and thus protects the metal of the table itself from any direct heating at any point save from such heat as it receives from the side Walls and the surfaces of the wall flanges 15, 15.

The upper portion of the chamber 13 is heated by blast flames of gas and air introduced through mixing burners 16, 16, etc., or in any other suitable manner, so as to produce an even and uniform temperature of the upper side walls and crown, the gases of combustion being led away through a flue 17 preferably located near the entrance end of the chamber adjacent to the spreading roll 2. lVhen the glass sheet is intro duced into the chamber on the table 1 the upper side thereofor that portion of it Within the chamber, comprising all of said side, save a narrow border around the sides and endsis quickly and eflectively reheated to a uniform temperature, thereby removing all the cold spots or other thermal inequalities of surface which have resulted from the operation of spreading the hot glass over the relatively cold table sur face. This action also softens the glass in the upper surface layers to a substantial depth and brings it to the condition of uniform plasticity required for the successful practice of the subsequent pressing operation. This reheating operation on the upper surface layers of the glass also affords opportunity for the equalization of temperature conditions in the body of the metal table and for the consequent disappearance of the convex warping or buckling of the table surface that always results from the rolling out of a mass of hot glass upon it, and which necessitates the use 'of special means for eliminating or compensating for such effect when the spread glass sheet is subjected to an immediate subsequent pressing. Such equalization of the table temperatures and with consequent restoration of the table surface to its original flat condition is-made possible in my reheating pro cedure by reason of the fact that glass itself is a very poor heat conductor and the spread sheet on the table surface acts therefore as an insulating plate or blanket to shut plasticity and temperature-this time and the heat of the furnace being so regulated as to further result in the equalization of temperature in the metal table and the restoration of the table surface to a flat condition-the carriage 5, with the table and the glass sheet supported thereon, is drawn forward out of the furnace 13 by means of a cable wound on a power driven drum 18, or in any other suitable manner, under the pressing mechanism. In this position it is supported on a platform 19 carried on track wheels 20, 20. The press mechanism may be of any approved construction, and as illustrated in the drawings Figs. 1, 2 and 4, it comprises a die supporting frame 21 pivotally hung (as shown innthe detail of Fig.

, 4) on four corner'plungers or posts, 22, 22,

etc., which pass through bearings 23, 23 on a stationary frame 24, which is supported in turn on the posts 25, 25 etc. The plungers 22 are each provided near their upper ends with a collar 26, and with a cylinder 27, containing a powerful spiral spring. 28 compressed between the collar 26 and the top cap 29 of the cylinder 27. The cylinders 27 are pivotally hung on links 30 that are attached in turn to the short crank arms 31, 31, mounted on cross shafts 32, 32, the latter being supported on bearings on the frame 24. Keyed to these cross shafts 32, 32 are two longer levers 33, 33', the outer ends of which are connected by means of links 34, with a piston 35, in the cylinder 36, said cylinder being also secured to the stationary frame 24. The weight of the piston 35 is sufficient to normally 11ft the die supporting frame and its attached parts and keep them in the elevated position shown in the figure.

When the reheated glass sheet has been brought to the pressing position under the die and die frame 21, air or liquid is admitted through suitable connections to the lower end of cylinder 36' and the piston 35 is raised by the pressure of the fluid so introduced. The upward movement of the piston 36 lifts the outer ends of the levers 33 and depresses the crank arms 31, 31 and the cylinders 26, 26 attached thereto, thereby permitting the suspended die frame 21 and its attached die to descend until it rests by gravity on the upper surface of the reheated glass sheet. The pressing die is always made smaller than the dimensions of the spread sheet, so that it will not come in contact with the outer cool border which has been covered while in the reheating furnace by the protecting ledges of the grooves 14, 14, or by the lintels 'of the openings in the end Walls, but will only contact with the central reheated and plastic surface of the glass. The pressingdie is also preferably adjustably supported on the die frame by means of screws so that it may on its descent contact simultaneouslyor nearly so--with the glass over its entire surface.

After the pressing die has been thus permitted to seat itself by gravity on the upper plastic surface of the spread glass sheet, a positive spring pressure is applied to the latter by the further upward movement of the piston 35 and the arms 33 and the consequent further downward movement of the cylinders 27 on the plungers 22, whereby the springs 28 are compressed between the collars 26 and the cap plates 29. The result of thus allowing the die to first seat itself uniformly on the plastic glass surface. and then subjecting it to. positive spring pressure, is to uniformly and accurately reform and refigure the free surface of the material over the entire portion subjected to the die action, without any further spreading of the soft metal and without introducing any internal. strain in the finished pressed sheet by reason of differences in temperature at different parts of the reformed material.

After leaving the die in contact with the pressed surface a sufficient length of time to produce a set such'as will render the die impression permanent the fluid is discharged from the cylinder 36 by opening an exhaust port, and the piston 35 descends carrying with it the levers 33, 33, and thus lifting the cylinders 27, 27, into contact with the collars 26, 26 after which the further descent of the-piston to the bottom of the cylinder lifts the die support and die to its original illustrated position. The pressed sheet is then slid endwise off the table 1 into the first chamber 37 of an annealing leer from which it is moved in suecession through the succeeding chambers 38, 39, 40, etc., and gradually reduced in temperature until it emerges at the end of the leerno t shown-in a condition for handling.

When the pressed sheet has been removed from the table the transfer carriage 19 on which the latter is supported in the press ing position is moved laterally on the tracks 41, until the section of track on which the carriage frame 5 is resting registers in position with the track section 42., 42. This IV to the dotted position V where it rests on a second transfer carriage 19% similar in all respects to the one indicated at 19. The second carriage 19 is then moved to its the position shown in Fig. 1 whereby the."

track section which it carries is brought" into registry with the track section on the" floor of the reheating furnace, and the table eaaevl frame and table supported thereby is brought into the first described position under the --roll 2 ready for the repetition of the various previously described operations of spreading the glass, reheating its upper surface and then pressing it to the desired configuration. At some stage of the movement from the position IV to the position V the table 1 is preferably reversed or turned over on its trunnion supports 11, 11 by withdrawing the catches in the arms 12, 1 2, so as to alternately expose the two sides of the table to the heat of the spreading operations. This assists in the equalization of heat and of temperature conditions throughout the body of the metal table support and in the consequent maintenance of the latter in a fiat unwarped condition for the pressing operations.

In order to carry on these successive operations with greater rapidity than could be secured by using one table and one tablesupport, it is desirable to provide two such combinations-of parts, so that one table may be brought into position for performing the spreading operation, while the other table is in the reheating chamber or under the press mechanism. Such an arrangement is illustrated in the drawings. If desirable still a third carriage and table might be added to the system, this third unit occupying an intermediate idle position on the track section 42 at the time the other two units are in the positions shown in Figs. 1 and 2 or in dotted positions II, IV or V.

In the form of apparatus shown in Figs.

'5 to 9 the steps of the combined spreading,

reheating and pressing process, are performed in the same order and sequence, and in the same manner as with the first described form of apparatus; and the table or tables on which the glass plates are supported during these operations are likewise sucessively moved from position I in which the sheet is spread, to position II, in which the upper side of the sheet is reheated, to position III, in which said reheated side is pressed, to positions IV, V and then back again to I. The form of'mechanism now to be described differs from the one previously explained only in detail features of the construction and arrangement of the parts by which these successive transfer movements of the glass supporting units are effected.

In the apparatus illustrated on the second sheet of drawings 1 indicates as before a table on which the molten metal is spread by means of a roll 2, the table being moved under the roll by a hydraulic ram 4 whose piston is geared to the roll in the same manner as illustrated in Figs. 1 and 2. As before the spreading roll 2 is preferably mounted as close as possible to one end of the reheating furnace 13' so that as the table with the sheet of glass spread thereon is moved forward under the roll it enters the chamber before the glass sheet has had an opportunity to cool to any appreciable extent. In this case the table is supported directly on wheels v1O secured to the edges of the table-see Fig. 7and these wheels roll on tracks located in grooves 14 in the side walls of the furnace chamberwhich are of sufiicient depth to also receive and protect the edges of the rolling table in the same manner as shown in Fig. 3. The length of the heating chamber is also made somewhat less than the length of the table 1 and slightly less than the normal length of the sheet of glass spread thereon so that when the table is in the position II within the furnace all parts of the table surface which are not covered with glass are protected from the heat of the chamber 13'. This chamber is top fired with gas and air through mixing burners 16 16 arranged at the end of the furnace farthermost from the roll 2 and the hot gases and products of combustion are led away through a stack flue 17 located at the end of furnace next to the said roll 2.

After the sheet of glass has been left in the'position II within the reheating chamber a sufiicient length of time to bring the top exposed surface layers thereof to the proper temperature and consistency the table is moved longitudinally from the said chamber to the position III-indicated in full lines in Fig. 7by means of a rack and pinion driven draft rod 18' secured to the end of the table by a detachable hook. In this position the table and the sheet of glass thereon is symmetrically positioned under the pressing die and its backing plate 21, which is hung on a series of bolts 22, 22, etc., secured to a rigid stationary steel framework 24', carried on columns 25 25 etc. The supporting die plate 21 is backed yieldingly by a series of strong spiral springs 28'28', etc., interposed between lug extensions on the die frame 27" and the end supports of the bolts 22' 22', etc.

The table 1 is supported in position under the pressing die on track rails 45 mounted on the upper end of posts 46, 46, the lower ends of which are supported on arms 47 47 keyed to heavy longitudinal shafts 48, 48 running parallel with the table. The bars or posts 46 are supported and guided at inter mediate points on their length by rocking arms 49, 49 the inner ends of which are pivoted to the bars 46, and the outer ends of which are pivoted on eccentrics 50,- 50 carried by a second set of longitudinal shafts 51, 51 parallel to the main shafts 48, 48. Secured to the opposite ends of the shafts 48, 48 are actuating levers 52, 52 the ends of which are pivoted in turn to the connected rods 53., 53 leading to pistons 54, 54 in cylinders 55, 55. When thesepistons aredepressed by the admission of fluid at the upper end of the cylinders the arms 52, 52 are moved outwardly and downwardly and the bars 46, 46 are thereby raised thus elevating the table 1 and the sheet of glass carried thereon and pressing the top surface of the latter against the lower figured or forming surface of the suspended die immediately above. The surface of this die is of course so adjusted as to make contact at substantially the same instant with all parts of the surface of the sheet which is to be subjected to pressing or reforming action, and the extent of the upward table movement is so regulated as to lift the back plate 21, and the die plate carried thereby off of its supports and compress the springs 28' to such degree as to exert the necessary forming pressure upon the top surface of the glass sheet. It will be observed that the link mechanism which communicates the motion from the actuating pistons 54, 54 to the bars 46, 46 and the track rails 45, 45, on which the tablerests is'of such design as to secure a constantly increasing leverage of action-or a constantly diminishing ratio of movement between the movement of the piston and the resultant motion of the table supportsand thereby secure the maximum pressure upon the surface of the glass at the end of the upward stroke and the completion of the refiguring or reforming operation. lit will also be observed, by inspection of the diagram of Fig. 8, that the movement of the bars 46, 46, is such that the upper end of these bars move in straight lines, and is such that when these bars are at their highest point of travel they are inclined at a small angle to the position which they occupy at the lowest point of their travel, the purpose of this angular change in position being to transfer the point of support for the table from the track wheels to the outer edges of the table itself and thus relieve the axle supports of these wheels from the strain of the pressing operation.

When the pressing operation is completed the air or fluid is allowed to escape from the cylinders 55, 55 and the table and table supporting mechanism are thereupon returned to their initial positions by the action of gravity. In this position the surface of the table is on a line with the floor of the first chamber 87' of the annealing leer so that the pressed and finished sheet can be shoved directly from the gtable into this chamber. The sheet is then advanced successively through the succeeding chamber 38, 39, 40',

preparatory to a repetition of the operations above described. The mechanism which is employed for this purpose in my second form of apparatus is constructed as follows: Below the table and the table supports which hold the same in pressing position, are two cylinders 56 and 57, the plungers of which are provided at their upper ends with forked t-shaped ends 56 and 59 which are adapted to engage with the trunnions on the ends of the table 1. When these plungers and heads are raised by bydraulic or pneumatic pressure, or in any other suitable manner, to their highest position the table 1 is lifted slightly. from its track supports 45, 45. The upper ends of the bars 46, 46 are then moved outwardly to clear the edges of the table by rotating the shafts 51 and the eccentrics 50 connected thereto by means of a cross-shaft 60 geared to the ends of the two shafts 51, 51 and operated by means of a hand lever 61. A second' set of shafts 62, 62 carry eccentrics 63, 63 the straps of which are connected by links 64, 64 to supporting track bars 65, 65, the lower ends of which are pivoted on the shafts 48, 48. The shafts 62 are coupled to the shafts 51 by means of suitable miter gear connections at the ends of vertical shafts 66, 66, so that the said shafts 51, 51 and 62, 62 are moved synchronously by the operation of the hand lever 61. in consequence of this the upper track supporting ends of the bars 65 are moved outwardly simultaneously with the outward movement of the bars 46. When the bars 65 and 46 and the track supports carried thereby have been thus moved outwardly the pressure in the cylinders 56 and 57 is reduced allowing the pistons of those cylinders and the table supported thereon to descend by gravity to the position 1V indicated in dotted lines in Fig. 7. In this position the weight of the table and the supporting mechanism therefor is sustained by stops 70, 71 which are held in position by bellcrank levers connected to a common hand lever 72. While being held in this position the table is next preferably revolved through 180 degrees on its supporting trunnions so as to bring what was originally its lower surface on top. The operating lever 61 is then moved to restore the eccentrics 50 and 63 to the initial position shown in Fig. 7. This brings the track supporting bars 46, 46 and the tracks 45, 45 carried thereby in a position to receive the table 1.in the next pressing operation; and also brings the bars 65, 65 and the track supported at the upper end of those bars into position to receive the table in lace in the lowered position of Fig. 7. he hand lever 72 isthen moved to the right thus allowing the pistons in the cylinders 56 and 57 to descend and lower the table from the dotted line position of Fig. 7 upon the tracks carried by the bars 65, and free the trunnions on the ends of the table entirely from engagement with the heads 58 and 59. The tracks on the bars 65 are in registry with tracks 42 which extend under the floor of the reheating furnace and terminate opposite another track section 73 which is mounted on a frame 74 carried by the pistons of two hydraulic rams 75, 76. When the table has been lowered on the tracks 65, 65after the above described reversalit is next moved from the dotted line position IV of Fig. 7 to the full line position indicated at V in Fig. 6, by means of a cable 77 attached to an eye at the end of the table trunnion and wound up on a power driven drum 78. After being brought to this position V the table is lifted by admitting water or air to the cylinders 75 and 76 until it occupies the dotted position I in which it is arranged to receive a fresh charge of glass preliminary to the repetition of the previously described cycle of operations. The ,uniform upward movement of the two pistons carrying the track frame 74 may be insured if necessary by connecting them by rack and pinion gear mechanism, the shaft 80 of which is preferably provided with a clamp 81 by means of which the track frame and table can be maintained rigidly in its elevated positionv without depending on the pressure of the fluid in the cylinders for that purpose-in which position the tracks supporting the table in the initial spreading position are in registry with the tracks in the side wall grooves 14 of the reheating furnace.

The various hydraulic or pneumatic or otherwise operated mechanisms which perform the successive functions of lifting the table from the position III to 'press the glass, of lowering the table from the position III to the position IV preparatory to its semirevolution and its subsequent movement to the position V, and of finally lifting it from the position V to the initial position I, may all be operated independently of each other by separately actuated control valves or other suitable control devices. But in order to economize power I prefer to employ a system of inter-connected control valves or devices by the use of which a portion of the water or compressed air-which is preferably employed for actuating the various pistons and piston mechanism already described-first introduced into the cylinders 55, 55 to lift the table in the pressing operation, is, on being discharged from those cylinders, led into the cylinders 56 and 57 and used to lift the heads -58 and 59 into position to engage the trunnions on the ends of the table in the position III. This may be conveniently effected by the valve and system of valve connections shown in Figs. 6 and 9 where, 85, 855, indicates a pistons of those eeann double or twin pressure fluid connection leading to a special five-way valve 86 (shown in diagrammatic section in Fig. 9) 87 and 88 indicated connections leading from this valve to the cylinders 5'555, and 5657, respectively, and 89 indicates an exhaust port. When the valve is turned to the full line position shown in the diagram of Fig. 9 the entry port 85 is in direct communication with the pressing cylinders 55, 55 through the valve passageway 90. When the valve is turned 90 degrees to the rightrd. e., clockwise-'the connection 87 to the pressing cylinders is in communication with the connection 88 leading to the transfer cylinders 56 and 57 and the fluid from the former is discharged in part into the latter thus elevating the heads 58 and 59 into engagement with the table trunnions, and reducin the pressure in the press cylinders sufiiciently to allow the table to begin its downward movement away from the pressing die. When the valve is turned 90 degrees more-to a position 180- degrees 5 from that indicated in Fig. 9--the entry port 88 to the transfer cylindersis placed in direct communication with the branch port 85' of the fluid pressure connection, (by means of the valve passage way while the port 87 of the pressing cylinders is simultaneously put in communication with the exhaust port 89 through the second valve passage 91. This entirely relieves the pressure in the cylinders 55, 55 and permits the table and the glass sheet supported mo thereon to drop entirely out of engagement with the pressing die, and at the same time increases the pressure in the transfer cylinders 56 and 57 suiiiciently to enable the port the weight the suspended parts on the trunnion bearing blocks 58 and 59. In the next position of the valve 86,-which is 45 degrees in advance of the'last described cglinders to entirely sup- 106 0 position or 235 degrees from the initial illus- 110 trated position of Fig. 9-all communication with the fluid pressure supply ports is cut off from both sets of cylinders and the valve port 88 leading to the transfer cylinders 56 and 57 is put in communication with the exhaust port 89, thus relieving the I pressure in the latter cylinders and permittingthe table to descend to the dotted line position of Fig. 7. The further movement of the valve 86 to a point 270 degrees in advance of the first illustrated position by-passes the two high pressure entry ports 85, 85' through the passage way 90 and leaves all other ports closed.

The continuous forward movement of the wheel"92 conveniently located with respect to the track shifting lever 61, and provided with suitable'stops or indicator devices to assist in the quick-and correct shifting of the valve.

The controlof the elevating or transfer rams 75, 7 6 is preferably effected by an or dinarytwo (or three) way valve 93 which reheating chamber 13'. As previously stated the drawings do not show and are not in tended to show all the specific details of construction of either form of apparatus which I have devised for the practice of my improved process, but only such features of mechanical structure as are necessary for; a full and correct understanding of the procedure which is to be followed in that practice.

The form of apparatus shown in the third sheet of drawings (Figs. 10 to 13) differs from the form previously described in having the reheating and the pressing stations arranged on opposite sides of the glass spreading station instead of having them both on'the same side and in consecutive or successive positions. In the arrangement shown in Fig. 10which is a longitudinal sectional elevation through the central plane of the apparatus-2 indicates the spreading roll which is adjustably supported as before at one end of the reheating chamber 13 and 21 indicates the die supporting frame of the press mechanism which in this case is placed in front of the spreading roll and only sufficiently removed therefrom to enable the molten glass to be teemed or deposited on the table 1 in advance of the roll 2 The glass is first rolled out on the table 1 by moving the latter to the right under the spreading roll, and this movement carrice the table with its sheet of glass thereon into the reheating furnace. This furnace-- as shown in Fig. 11-is somewhat similar in its cross-sectional form to that which I use in my second form of apparatus; 11. 6., it has an upper heating chamber 13 of somewhat smaller size than the sheet of glass spread onv the table 1 and has two longitudinal grooves or recesses 14 14 in the lower portion of the sidewalls for the reception and protection of the edges of the table and of the supports therefor. The furnace in this caseis of the regenerative type of construction with reversible fuel and stack ports 16 17 on its opposite sides.

After the table has been moved into the reheating chamber to the position l[Iindi= cated in dotted lines in Fig. 10-and has'r emained there a suflicient length of time to allow the upper exposed surface layers of the spread sheet of glass to become thoroughly and uniformly reheated and softened, it is drawn back under the spreading roll (which has in the meantime been slightly raised) and brought to the pressing position III,

under the die supporting frame 21 The reheated surface is then molded to the required configuration by pressing the die on the frame 21 against it in any suitable manner. The mechanism which I show for this purpose in Fig; 10 comprises a fluid pressure cylinder 36 containing the piston 35 which is connected by rod 3& with a lever 33 keyed to the left-hand one of two cross shafts 32 32 These cross shafts, together with the cylinder 36 are mounted on a, framework 24 .that is carried on posts 25 25 etc. They carry short crank arms 31 31 which are connected by links 30 30 to cylinders 27 27 etc., of the same construction as that shown in detail in Fig. 4. The cross shafts 32 are also provided with levers 95, 96, connected so as to move in unison by the bar 97. The die and die frame 21 (which are suspended on the plungers or posts 22 etc., passing through the cylinders 27 etc.) are normally held in elevated position either by counter-weighted levers on the shafts 32 32 or preferably by connecting the end of the cylinder, back of the piston 35 with an exhaust or vacuum pump. When it is desired to depress thedie and die frame for the purpose of pressing the reheated glass surface, the exhaust connection is closed and fluid under pressure is admitted to the end of the cylinder, thereby causing the piston 35 to move to the left and depress the cylinders 27 27 etc., and with them the suspended die frame 21 After pressing the figured glass plate is slid longitudinally ofi the end of the table 1 into the first chamber 37 2 ofthe annealing leer. The table 1 is then moved forward until its right hand end is below the spreading roll 2 ready for a new cycle of operations.

In order to provide for reversing the glass supporting table 1 and in order to permit of the use of two or more independent tables in succession, I mount each table 1 on trunnions which are supported on the cross bars 11 11 of open rectangular frames, mounted on track wheels 10 10 etc. The section 19 carried by track wheels 20 20 etc.

When I desire to use two tables in alternate succession with this form of apparatus I connect two such transfer carriages together by rods 100as shown in Fig. 12-so that the lateral movement of one carriage out from under the pressing mechanism, automatically brings the second carriage and the table carried thereby to the position shown in Fig. 10. When either carriage is moved to its extreme lateral position (either to the position IV of Fig. 12, or to the symmetrically opposite position on the other side of position III) the table on that carriage is entirely out from under the press mechanism and can be easily reversed on its trunnion bearings within the open rectangular base of its supporting carriages by releasing the catches which hold said table in a horizontal position either side up. (See Fig.

The mechanism for moving the table supports and table may be of any desired character. I have shown two different forms of mechanism for the purpose in Figs. 10 and 13. In the first form I provide a bar 101, the lower end of which is constrained to move in a straight line by attaching it to a plate 102, sliding in ways 103, and the center point of which is constrained to move in an arc of the dotted circle whose center isat c. I nder such circumstances the upper end of the bar 101 will travel in a straight horizontal line passing through the point a, and may be connected directly to the table carriage by means of a. detachable hook 104 engaging with an eye 105 on the carriage. To move the bar,and the carriage thus coupled theretoin either direction I mount a motor 106 directly on the bar and connect the shaft of said motor by suitable reduction gears to a pinion 107, that engages with the segmental rack 108.

Instead of the form of actuating mechanism just described I may use the form shown in Fig. 13 which consists simply of a triangular carriage 109 slidably mounted on ways 110 and moved along the latter by a pinion 111 mounted in hearings on the carriage 109 and engaging with a stationary rack 112. The pinion 111 is driven as before by a motor 106', attached directly to the movable carriage 109.

As will now be readily understood by those skilled in this art various other forms of apparatus than those above specifically illustrated and described might be employed in carrying out my improved process; and various mechanical features of these different forms of apparatus may also be varied widely without altering the essential characteristics of the operations and procedure which distinguish my present invention.

As already indicated-and as now will be apparent-the step which most clearly differr ates the process above described from prior art practices is the reheating of ,the upper side of the spread glass sheet before aaaaa'ri the pressing operations is performed. This reheating of the upper exposed side not only removes the chilled skin formed during the spreading action, and brings all parts of the surface to a substantially equal temperature, but also allows the upper layers of the sheet to be brought to a higher temperature than the molten mass originally possessed; and thereby brings this upper side to the best possible condition for subsequent pressing operations. This reheating operation therefore enables me to perform the preliminary spreading of the glass at a lower temperature than would otherwise be possible, if the spread sheet was to be immediately subjected to pressing, and it further enables me to form a very thin sheet of any desired size and afterward free the upper surface of that sheet from the combined chilling effects of the roll and table support so as to bring the entire reheated portion to proper condition for subsequent pressing operations and reform that surface by pressure to the most intricate pattern desired. The reheating has a further advantage of freeing the spread glass blank from any initial strain that may be imparted to it by the spreading of the molten mass upon the relatively cold table support, and thereby further aids in the subsequent production by pressure -of a finished article free from any internal strain of formation. In the ordinary operation of spreading out a sheet of glass upon a table or other suitable support by means of a roll, or other spreading instrumentality, the operation must be carried on at a relatively slow speed on account of the softness and viscosity of the unformed molten mass, and when this spreading is performed in the open air the first formed end of the spread sheet is frequently cooled by radiation and conduction to sucha point that it has lost the capacity for further reformation by pressure-in fact has lost its color or become nearly black -before the spreading operation has been completed. This is almost certain to be the case when the spread sheet is very thin-Jess than inchor when the completed sheet is of considerable length greater than 8 feet. I have previously perfected methods which enable me to press very thin sheets or very large sheets by acting upon said sheets with a series of dies which descend upon and press successive sections of sheet immediately after the formation of the same; but this method has some disadvantages, chief among which is the difficulty of avoiding lines of imperfect or incomplete pressing action at the points of juncture between the contiguous and successively depressed pressing die elements. My present process, in which the reheating step is introduced eliminates the above difiiculties in the production of a pressed article or sheet of any desired size and of any desired thinness, as well as enabling me-as above indicatedto perform the preliminary spreading operation at a lower temperature, and a slower speed than would be possible in the practice of any present method, and also enabling me to bring the surface layer or side to be operated upon to a softer and a better condition for subsequent pressing ope 'ations than is possible in any one of my previously devised processes in which the article is pressed in the condition in which it is left by the preliminary spreading operation. And as further explained the reheating operation when performed in the manner described, giyes the table support an opportunity to return from the warped or buckled condition (to which it is brought by the spreading of the hot molten glass on its upper surface) to its normal fiat condition before the glass is brought in coi tact with the pressing die, and thereby eliminates in whole or in large part the difficulties experienced in obtaining substantially simultaneous contact between the glass and the die forming surface such as is necessary in securing large pressed sheets of perfect figure over their entire surface. Further advantages both of the process and of the mechanism employed in its practice such as greater speed of operation due to the employment of more than one spreading table, the reversal of the tables between spreading operations-so as to obtain longer and more efficient table service etc. etc-will readily suggest themselves to those who are experienced in the production of the class of products for the manufacture of which this invention is designed. These products may have either plain surfaces" semiplate; pressed wire glass, etc.-or gured surfac es prism glass, ornamental glass, etc-and may be made of either transparent or of opaque vitreous material.

What- I claim is v 1. The method of manufacturing pressed glass sheets or plates which comprises the preliminary spreading of the molten material to sheet form, the subsequent reheating of one side of the spread sheet to a substantially uniform temperature over the entire area to be subjected to pressing operations and the final pressing of the reheated surface. 2. The process of manufacturing pressed sheet glass products which comprises the following stepsfirst"spreading a mass molten glass to sheet form, second reheating one side of the spread sheet before the material has lost plasticity or acquired a set, and third, subjecting the reheated surface to die pressure whereby itis caused to acquire the configuration of the die surface.

3. The process of making pressed glass plates which consists in first rolling out a mass of molten glass into sheet form on a supporting surface, next transferring the spread sheet while still on its support to a furnace and therein reheating the upper free side of the sheet, and then transferring the sheet and its support to a pressing device and therein subjecting the reheated glass layer to sufficient pressure to cause it to assume the configuration of the press die.

4. The method of making pressed glass plates which comprises the rolling out of a mass of molten glass on a table, then immediately transferring the table and the sheet of glass supported thereon to a furnace and therein reheating the free upper side of the spread sheet to a uniform temperature, and then transferring the sheet while still on its original support to a press mechanism and ressing the reheated surface layer to a new configuration.

5. The process of manufacture of pressed glass sheets or plates which consists in depositing a mass of molten glass on a supporting table surface, spreading the glass to sheet form on the support, transferring the support with the spread sheet thereon to a furnace and reheating the upper free side of the hot glass sheet before it has lost its plasticity or become set, and then subjecting the reheated surface to press action and thereby refiguring it to a new surface layer contour.

6. The process of making pressed sheet glass which comprises the spreading of the glass to sheet form the reheating of one side of the spread sheet to a substantially uniform temperature before the spread sheet has lost any appreciable quantity of its initial heat, and the pressing of the reheated surface layer to a new configuration.

7. The manufacture of pressed glass plates or sheets which comprises the spreading of a mass of hotglass to sheet form, the reheating of one surface of the spread sheet to a higher temperature than that which it possessed originally, and the pressing of the reheated surface to a different configuration.

8. The herein described )rocess of making pressed glass sheets which consists in first spreading the material to sheet form; then transferring the spread sheet to a furnace and there reheating the central portion of one side of the sheet to bring it to a substantially uniform temperature, while protecting the outer boundary edges of the said sheet from such reheating action; and then removing the sheet from the furnace and pressing the reheated portion thereof to final form.

9. The herein described process of making pressed glass sheets which comprises the steps of spreading a mass of molten glass to sheet form on a supporting table; next transferring the spread sheet and its support to a. furnace and reheating the central portion of the upper side of the sheet, while protecting the edges of the sheet and the supporting surface therefor from such reheating; and then subjecting the reheated surface portions of the glass to a pressing operation.

'10. The process of manufacture of a succession of pressed glass sheets which comprises the steps of depositing a mass of molten glass on a table support; spreading it to sheet form thereon; next reheating the upper side of the spread sheet; next pressing the reheated and softened portions of the glass to impart a new configuration thereto; next removing the pressed sheet from the table support and reversing the latter; and then repeating the above described steps in the formation of another sheet.

11. The process of manufacture of a succession of pressed glass sheets, which comprises the steps of rolling out a mass of glass on one sideof a reversible table support; next subjecting the rolled out mass and the support therefor to a heating operation to reheat and soften the upper side of the glass sheet and to equalize temperature conditions in the table support; next pressing the reheated and softened surface layer of glass to the desired configuration; next removing the pressed sheet from the table and reversing the latter; and then repeating the above described series of steps in forming another sheet.

12. The process for the manufacture of pressed glass plates which comprises the spreading of a mass of glass to sheet form on a metal table; then heating the upper side of the spread glass sheet, and simultaneously heating the lower side of the table to equalize temperature conditions therein and therebyeliminatethe warping thereof; and then transferring the table and the sheet carried thereby to a press mechanism and subjecting the reheated portion of the glass to die pressure, to reshape and finish it.

13. The process of making pressed glass plates which consists in rolling out a mass of glass on a supporting table, transferring the table with the glass supported thereon to a furnace and then subjecting the upper free surface ofthe hot spread sheet to sufficient heat to raise its temperature.above that at which it was initially formed, and thentransferring the glass sheet while still on its supporting table to a press and subjecting the reheated free surface to the pressure of a die whereby the desired configuration is imparted to the plate or sheet.

14. Apparatus for the manufacture of pressed glass plates or sheets which comprises a glass receiving table, a spreading mechanism, a furnace, a press mechanism and means for moving the table relatively to the other element substantially as described and for the purposes specified.

15. In apparatus for the manufacture of pressed glass sheets the combination of a glass receiving table, a spreading mechanism movable relatively to the table and in synchronism therewith, a furnace whose horizontal area is slightly less than the glass receiving area of the table, means for positioning the table centrally within the furnace chamber, and other independently operating means for transferring the table from its position within the furnace to a position under a pressing mechanism.

16. In apparatus for the manufacture of pressed glass plates, the combination of a glass receiving table, a roll for spreading a sheet of glass thereon, a press mechanism, and means intermediate the spreading roll and the press mechanism for simultaneously heating the upper side of the spread glass sheet and the lower side of the table support therefor.

17. Apparatus for the manufacture of pressed glass plates or sheets comprising a furnace a spreading roll mounted at one end of the furnace, a pressing mechanism at the opposite end'of the furnace, a movable glass supporting table, means for moving said table under the spreading roll and into the furnace, independent means for moving the table out of the furnace and under the pressing mechanism, and still other means for returning the table from the pressing mechanism to its initial position under the spreading roll without passing through the furnace.

18. Apparatus for the manufacture of pressed glass sheets having in combination a movable glass supporting table, a furnace having an upper heating chamber of somewhat smaller internal dimensions than the table, a spreading roll mounted above the table at one end of the furnace, means for moving the table under the roll and into the furnace, a pressing mechanism mounted at the end of the furnace opposite the spreading roll, means for moving the table from the furnace and under the pressing mechanism, and independent means for retprning the table from its position under the pressing mechanism to its initial position under the spreading roll without passing through the furnace.

19. In an apparatus for the manufacture of pressed glass plates or sheets the combination of a movable glass supporting table and aroll for spreading a sheet of glass. thereon, a furnace and means for moving tion under the pressing mechanism to their position under the spreading mechanism.

21. In an apparatus for the manufacture of pressed glass sheets or plates the combina-- tion of a movable glass supporting table, a spreading roll, a furnace having an upper heating chamber of sma'lier internal dimensions than the table and With grooves in the side of said furnace for receiving and protecting the edges of the said table, means for moving the table under the spreading roll and into the furnace, a pressing mechanism means for moving the spreading table out of the furnace and under the pressing mechanism, and means for returning the table from its position under the pressing mechanism to its initial position under the spreading roll.

22; In an apparatus for the manufacture of glass plates, the combination of a reversible glass supporting table and means for holding the table either side up, With'a spreading roll mounted above the table, a furnace, a pressing mechanism, a series of track sections in registry-With each other for supporting and guiding the table in successive positions under the spreading roll, into the furnace, and out of the latter under the pressing mechanism, and mechanism for moving the table to the said successive positions and back again to its initial position under the spreading roll.

23. In an apparatus for the manufacture of pressed glass plates or sheets, the combination of a series of reversible glass supporting tables, a spreading roll, a furnace with an upper heating chamber of smaller internal dimensions than the tables, a pressing mechanism, a track system for receiving and guiding the tables to successive positions under the spreading roll, into the heating chamber, and under the pressing mechanism, and means for moving said tables in regular order to such successive positions and returning them to the initial position under the spreading roll.

24. In apparatus for-the manufacture of pressed glass plates or sheets the combina-' tion of a twin faced glass receiving table, a movable carriage therefor, means for supporting and holding the table either side up on the carriage, a spreading roll mounted on an independent support and capable of verticaladjustment with respect to the carriage and table, means for moving the carriage and the table carried thereby under the spreading roll and into a reheating furnace, a pressing mechanism and means for moving the carriage and table out of the reheating furnace and under the pressing mechanism.

25. In an apparatus for the manufacture of pressed glass plates or sheets a reversible table, means for supporting said table either side up, means for spreading a sheet of glass on the 'said table, means for reheating and softening the upper side of the spread glass sheet to a substantially uniform temperature over substantially its entire surface area and means for subjecting the reheated portion of the glass to the action of a die for shaping and figuringthe softened surface layers.

26. In an apparatus for the manufacture of pressed glass plates or sheets the combination of a double faced table, a support for holding said table either side up, a spreading roll adjustably mounted above said table, means for imparting simultaneous movement to the table support and the roll, a furnace for reheating and softening the upper side of the glass sheet after it has been spread on the table, a press mechanism for shaping and finishing the reheated and softened surface layers of the glass sheet, and a system of "transfer devices for moving the table support successively into registry with the furnace, and the pressing mechanism and then back again under the spreading roll.

27. In an apparatus for the manufacture of pressed glass sheets the combination of a reversible table, a traveling support therefor, a spreading roll, afurnace, a pressing mechanism, and means for successively 105 moving the support and the table under the spreading roll, into the furnace, then under the pressing mechanism, then to an idle station at which ,the table can be reversed, and then back/again to the first po- 11 sition under the spreading roll.

28; In apparatus for the manufacture of pressed glass sheets the combination of a twin faced reversible glass receiving table, means for spreading a sheet of glass 15 thereon, a furnace station, a pressing sta} tion, a reversing station, and means for movin the tablesuccessively to these stations or the purposes specified.

29. In an apparatus for the manufacture of pressed lass sheets the combination of a glass receiving table, a roll for spreading a sheet'of glass thereon, a heating device and a pressing device; with two sets of transfer devices, one for moving the table 125 successively under the spreading roll, into the furnace and out of the furnace under .the pressing device, and the other for movinitial position in front of the spreading roll.

30. In an apparatus for the manufacture of glass sheets the combination of a table support, a spreading device, a heating furnace, a pressing device, and two sets of transfer tracks at right angles to each other, one of said sets being adapted to carry the table support successively from its initial position under the spreading device, into the furnace, and then out of the furnace under the pressing device and the other set being adapted to carry the table support away from the first set of tracks to an idle station and then back again to its initial position under the spreading roll substantially as described and for the purposes specified.

81. In apparatus for the manufacture of glass sheets the combination of a reversible glass receiving table, a spreading device for forming a sheet of glass on the upper side of the table, a heating device adapted to simultaneously heat the upper side of the sheet of glass spread on the table and the lower side of the table, a pressing device, a transfer mechanism for moving the table successively from its initial position under the spreading device to the heating device, then from the heating device to the pressing device, and an independent transfer mechanism for ymoving the table out of the line of movement from the spreading device to the pressing device and then returning it to its initial position under the spreading device.

In testimony whereof I have hereunto set my hand.

FRANK L. O. WADSWORTH. \Vitnesses M. M. SCHINNELLER, SUE B. FRITZ. 

